Get an enum field from a struct: cannot move out of borrowed content

Question

I\'m new to Rust and trying to wrap my head around the ownership/borrowing concept. Now I have reduced my code to this minimal code sample that gives a compile error.

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Answer 1

I'm still in the everything is copied by value mindset, where it is perfectly legal to do self.color as that would get me a copy of Color. Apparently, I am wrong. I found some other questions about this same error on SO, but no solution to my issue.

Anything that can be copied in rust must be explicitly mared with a trait Copy. Copy was implicit in the past but that was changed (rfc).

As I understand it, the field is owned by whomever owns the Display. Since I only borrowed a reference to the Display, I don't own it. Extracting color attempts to transfer ownership of the Color to me, which is not possible since I don't own the Display. Is this correct?

Yes. When you encounter this error there are three possible solutions:

• Derive the trait Copy for the type (if appropriate)
• Use/derive Clone (self.color.clone())
• Return a reference

To solve this you derive Copy for Color:

#[derive(Copy, Clone)]
pub enum Color {
    Blue         = 0x1,
    Red          = 0x4,
}

This is the same as:

impl Copy for Color {}